DE1642633C - Process for the production of baker's yeast and its use for the production of baked goods - Google Patents

Description

The invention relates to a method for producing a new baker's yeast by growing a new one Yeast strain according to usual methods.

Various baker's yeasts of very good quality are already known, e.g. B. Saccharomyces cerevisiac Ng 740 and Saccharomyces cerevisiae Ng 1777, which are described in Belgian patent 620,618 are.

These yeast hybrids are characterized by the fact that they are in the dough after consumption of the sucrose and Fructose polymers from flour show a rapid transition to the consumption of maltose.

The lack of maltase and maltose permease in common baker's yeast has been overcome in these hybrids.

The previously known baker's yeast belonging to the Saccharomyces cerevisiae species to which the aforementioned hybrids also belong are able to to ferment only a third of the raffinose contained in molasses, as a result, part of the original r .materials are unused and the yeast yield is reduced.

Raffinose is not found in cane sugar molasses. Beet molasses, on the other hand, contain 0.5 to 4.2% raffinose, with an average value of 1.55% based on 100% dry matter. Under abnormal Under certain circumstances the content can rise up to 10%. The average dry matter content of molasses is 80.9%. In residue molasses, such as those obtained after the delight of molasses, 15% Raffinose present. When raw sugar is refined by dissolving and recrystallizing it, molasses falls on. which has a higher raffinose content than normal beet molasses (cf. "Die Molasse", H. O 1-brich, Inst, for fermentation trade, Berlin 1956, pp. 9, 12 and 13; "The yeasts", Nuremberg, 1962, Vol. II, P. 49).

In order to obtain a higher yield of baker's yeast, based on the raffinose contained in the molasses, the use of SaccHaromyces carlsbergensis would be recommended. This yeast is able to To ferment raffinose completely. The difference between Saccharomyces carlsbergensis and Saccharomyces cerevisiae is commonly seen in the ability of Saccharomyces carlsbergensis to develop melibiosis fermentation and raffinose (cf. "The Yeasts, a Taxonomic Study", Lodder, Kreger - van, Rij, Amsterdam 1952). Another distinction that is often made is that Saccharomyces carlsbergensis addressed as bottom-fermenting yeast ivel. "Die Hefen", Nuremberg 1962, Vol. II, p. 271; JCte t s ch mar, »Yeast and Alcohol«, Berlin 1955, P. 73.

Top-fermenting yeasts ferment raffinose not only up to a third and melibiose ever ds them the enzyme melibiase missing bottom-fermented yeast, however, can Raffino.se completely ferment (cf. Ullmann's Encyclopedia of Industrial Chemistry, 3rd Edition, Vol. 4 [19531, p 379, and Vol. 8 [1957], p. 453; Kretschmar, "Hefe und Alcohol", Berlin

ίο 1955, pp. 73 and 180).

The yeast used in bakeries is a top-fermenting living culture yeast of the Gattuüg Saccharomyces. cerevisiae. _t

The literature shows that the bottom-fermenting brewer's yeast Saccharomyces carlsbergeasi? is less suitable as baker's yeast. Saccharomyces carlsbergensis is sensitive to agents that change the osmotic pressure, especially to salt, and as a result cannot be a good substitute for baker's yeast (cf. Kretschmar. "Yeast and Alcohol". Berlin 1 ^:) 55, p. 386 ).

As a result of the development of special baker's yeast, the use of brewer's yeast Saccharomaces carlsbergensis quickly taken off in bakeries (cf. Kretschmar, loc. cit., p. 386ff).

If one considers the properties of Saccharomyces carlsbergensis to completely ferment raffinose in the If you wish to utilize baker's yeast production, it would be desirable to have the properties of a very good baker's yeast by hybridization in Saccharomyces carlsbergensis to introduce.

The crossing of Saccharomyces cerevisiae with Saccharomyces carlsbergensis is known (cf. »The Hefen ", Nuremberg [1960], vol. I. p. 194; C. L i η d egren, C. C. Lindegren, and S. Spiegelman, Proc. Nat. Acad. May be. U.S.A., Vol. 30 [1944], p. 346). It is known that Saccharomyces carlsbergensis is melibiose positive; H. is able to break down melibiosis and ferment. Saccharomyces cerevisiae is melibiose negative. The one formed by crossing Hybrid is melibiosis positive. This and other crossbreeding analyzes showed that the ability to Breaking down and fermenting melibiose is dominantly inherited.

If baker's yeast utilizing raffinose is to be obtained, it is necessary during hybrid formation and to control the backcrossing of Saccharomyces carlsbergensis and Saccharomyces cerevisiae, whether the spores formed by the intermediate hybrids are able to ferment melibiose because these Fermentation is not the common property of the parent strains. The crossing is carried out by combining suitable monospore cultures of different mating types from different Yeast strains (cf. Lindeeren, »The Yeast Cell, its genetics and cytology ", St. Louis 1949).

The hybrids obtained in this way can after fermentation be propagated for further attempts. The yield and stability of the yeast obtained be determined. Baking tests are also carried out.

The object of the invention was therefore to provide a method for the Hei position of a new pressed or baker's yeast create, the raffinose completely fermented, thus in raffinose-containing molasses in high yield Can be bred and has a good durability (standing quality) and constant, powerful driving force owns. This object is achieved according to the invention

solved that Saccharomyces carlsbergensis Ng3010 breeds in the usual way.

The Saccharomyces strain used according to the invention carlsbergensis Ng 3010 is a hybrid obtained in the manner described above.

The values given below refer to yeast propagated in a mixture of molasses, that from 20% sugar cane and 80% beet molasses and a sucrose content of 50%, a raffinose content of about 1% and an assimilable Has a nitrogen content of 0.7%.

The yeast is multiplied in such a way that a protein content of 52.5% ± 1% and a P ₂ O ₅ content of 3.3 ± 0.2% - calculated on dry weight - is obtained. The yield is expressed in grams of yeast with 28% dry matter, which is obtained from 100 g of molasses. Yield and stability et ^r known baking yeasts are already quite favorable, since it is becoming increasingly difficult to improve these properties, the yield and stability of the yeast ernndungsgemäß produced is to be regarded as a significant advance.

Regarding the yeast yield, based on the nutrient medium, It must be pointed out that in the Any improvement in yeast production yield is of paramount importance, and practice any improvement even if the increase in yield is in the order of magnitude of, for example, only 1%. To this Way, an additional amount of end product is obtained from the same amount of starting material, Of course, in practice it is very difficult to see the reality of such proportionately to demonstrate minor improvements, among other things as a result of the inaccuracy of the measurement and weighing methods in industrial production. When testing on a laboratory scale or in a test department that is specially equipped for this purpose, it is easily possible to demonstrate the substantiality of the improvement in the yield, such as that from those given below Values.

The other properties required of baker's yeast such as: B. quick transition to the Maltose fermentation and a strong and constant development of gas in the dough and good suspensibility in an aqueous medium, are also present in their entirety and correspond very well to the Properties of the well-known baker's yeast. The yeast is grown by customary methods, preferably according to the feed process (cf. J. W h i te, "Yeast Technology" London 1954).

The yeast strain Saccharomyces used according to the specification carlsbergensis Ng 3010 has the great advantage that it is fermented by melibiosis can be clearly identified. This yeast is under the specified Number on file with the C.B.S., Yeast Division, Delft.

A number of determinations were carried out to characterize the new yeast hybrids, see above that it is possible to determine whether the baker's yeast on the market is this hybrid.

More than 650 moncspore cultures were isolated, of which 500 germinated and followed Criteria were examined.

65 1. Pairing type

The mating type of the monospore cultures is determined by thoroughly mixing a small one Amount of a young malt agar culture to be tested Yeast on a malt agar plate with a small amount of yeast from a young malt agar culture of Ng3 = alpha type or Ng 10 = a - type (deposited at the C-B. S. under these numbers) in test tubes. After approximately 4 to 5 hours of incubation at 25 ° C, the mixtures become microscopic for the presence of zygotes. If zygotes are formed with Ng3, then the monospc belongs to: sn culture for mating type a, if rait Ng 10 Zygotes are formed, it belongs to the mating type alpha. If there is no mating reaction in both Tubes can be observed, the monospore culture is to be regarded as sterile. Now the percentage can of alpha cultures, ä cultures and sterile cultures, that of a large number (approximately 500) of monospore cultures a single yeast strain is obtained. For a given yeast is the percentage of a- and alpha-K.u! tures «md that The relationship between the number of alpha and alpha cultures is practically constant and characteristic.

2. Sporulation of the monospore cultures

As many baking yeasts are not diploid. but are triploid or even tetraploid, it is possible that the Mcnospore cultures have a higher number of chromosomes than corresponds to a chromosome set . Hence it is that in this case too they can form spores. Especially from the sterile ones Monospore cultures that are diploid and of the (a, a! Pha) -type can be, can throw sporulation expected. However, it has been found that also divide Monospore cultures with a mating reaction are those cultures which form spores. from 500 monospore cultures can in this way be the percentage of sporulated monospore cultures to be established. A 24 to 48 hour old monospore culture on malt agar is used for inoculation of an acetate-agar inclined tube (d) vei turns. Incubation takes place at 25 ° C. After 2 days, after a week and after 14 days checked whether spores are formed in the tube or not.

3. Behavior of the monospore cultures with regard to Drsthic biotin

About 2 ml of a suspension of a young malt agar culture in a physiological salt solution is mixed with 20 ml of melted biotin agar (b), then cooled to about 47 ° C. This mixture is poured into a Fetrischaie. After the agar has solidified, paper disks are placed on four places on the agar plate, two of which contain 0.05 ml of a solution of 0 ^ g / ml biotin and 0.05 ml of a solution of 0.5 μg / ml desthiobiotin were soaked. After approximately 24 hours growth at 30 ⁰ C, can be found from the WachstumsflLchen whether the Htfestamm is capable of utilizing desthiobiotin instead of biotin. The percentage of desthiobiotin-negative monospore cultures and desthiobiotin-positive monospore cultures (biotin monospore cultures) that a yeast can produce is constant. There is therefore a property here which allows a clear distinction between the yeast strains.

4. Percentage of Spore Germination

From a sporulating yeast culture, the spores of four-spore asci are placed in yeast-water-glucose-peptone drops (c) isolated using a micromanipulator. The cultures are incubated at 25 ° C. When the culture in the drop has grown sufficiently, it is cleared with the help of a sterile filter paper in a small Freudenreich flask with about 10 ml yeast water-glucose-peptone or with Malt extract transferred. After it has grown sufficiently, the yeast is placed in a malt-agar tube The number of isolated spores determines the percentage that will develop into a colony and good growth determined even after being placed in the Freudenreich-flask-showing spores. This property is not very reliable. For some yeasts, the germination percentages are too close to each other to be useful for differentiation.

5. Behavior of monospore cultures
versus melibiosis

The growth of monospore cultures Glucose agar (s) and on melibiose agar 'cj compared (about 500 times).

With the help of these values the melibiose-utilizing spores can be determined quantitatively, again by incubating at 25 C in a melibiose-containing one Yeast autolysate (0 in Durham tubes.

The composition of the nutrient media used is as follows.

a) Difco malt extract:

55 g Difco malt extract,

20 g Difco-Bacto-Agar, 1 liter of distilled water,

sterilized: at 110 C for 30 minutes.

b) biotin agar:

Twice per liter of distilled water:
3 g ammonium sulfate, 2 g KH ₂ PO ₄ , 1 g sodium acetate 3 H, O. 0.25 g magnesium sulfate 7H ₂ O, 0.175 g calcium chloride · 6H ₂ O, 10 mg 1-tryptophan, 5 mg inositol, 300 mg dl-aspartic acid, 20 g glucose. 0.5 g difcocasein hydrolyzate (vitamin-free), 1 ml solution of trace elements, containing:

1 mg MnCl ₂ · 4H ₂ 0.1 mg ZnSO ₄ · 7H ₂ 0.0.1 mg KI, 0.5 mg FeCl ₃ -6H-O, 1 mg TlCl ₃ , 1 mg H ₃ BO ₃ , 0.1 mg CuSO ₄ ■ 5H ₂ O.
20 μg p-aminobenzoic acid, 40 μg vitamin B, 40 μg calcium pantothenate, 500 μg / ^ - alanine, 100 μg vitamin B ₆ , 100 μg nicotinic acid amide, 20 g Difco agar. The medium is adjusted to a pH of 4.5 and sterilized at 110 ° C for 30 minutes.

c) Yeast water glucose peptone:

1 liter of tap water, 10 g of Difco yeast extract, 20 g of peptose, 20 g of glucose; the nutrient medium is adjusted to a pH value of 5 and ^{sterilized at HO 0} C for 15 minutes.

d) acetate medium:

15 g Difco-Ag'H, 6.63 g sodium acetate. 3H ₂ O, tap water up to 11, the medium is adjusted to a pH of 6.5 to 7.0 and ^{sterilized at 120 °} C. for 20 minutes.

e) glucose or melibiose agar
6.7 g yeast nitrogen base (Difco),
20 ε glucose or melibiose,

V rtrt- · - ^

55

60

65 20 g Difco agar,
11 distilled water. The nutrient medium is sterilized for ^{30 minutes at RO 0 C,}
f) Hele autolysate and melibiose liquid:
1 kg compressed yeast in 11 tap water 24 hours 50 ⁰ C. Then, the heated Geroisch is boiled and centrifuged, the medium is mixed with 1-n NaOH to a pH value of 6 is set. It is then boiled again and nitrated. Then it is diluted 1: 5 with tap water. After adding 2% melibiose, the solution is ^{sterilized in Durham tubes at 120 °} C. for 20 minutes.

Table I.

Ng 3010 Error means
Π 1. Percentage of Mating types alpha, a and 0 51.7% α 0.78 36.8% a 0.85 11.5% 0 1.8 2. alpha: a 1.41 0.07 3. Sporulation 0 91.1% 0.64 4. Desthiobiotin positive 82.4% 1.4 5. Spore germination 74.1% 2.9 6. Melibiosis positive 78.6% 3.25

According to the usual process for baker's yeast of inflow fermentation with molasses with a content of A number of yeast strains were propagated at 1.2% raffinose.

The experiments were repeated eight times in order to obtain reliable results. Ss will be the following Get results.

Table II

Ng 3010 Yeast yield, Ng 740 related to Hello Ng 1777 used ATCC Molasses. % Saccharomyces carlsbergensis 13602 99.9 Saccharomyces cerevisiae ATCC 96.0 Saccharomyces cerevisiae 13601 98.8 Saccharomyces cerevisiae 97.2 Saccharomyces cerevisiae 97.3

As stated above, the differences found must be new, real, and economically significant be considered.

For every 100 yeast produced, a positive difference in yield of 1% of the yield makes an additional one Production of 1 t from the same amount of raw material. The difference in yield becomes even bigger and even clearer if the cultivation in a nutrient medium with molasses with a higher Raffinose content is carried out.

To demonstrate the improvement in the yeast yield in the method according to the invention to be completed, two more breeding experiments were carried out, namely with Saccharomyces cerevisiae Ng 1777 and with Saccharomyces carlsbergensis Ng 3010. During the first All sugar was breeding in the form of

Molasses used. In the second breeding attempt, 95% sugar in the form of molasses and 5% used in the form of raffinose. Calculated on raw material containing sucrose and raffinose the following yields were obtained:

Table III

With Raffinosc

enriched

molasses

Saccharomyces cerevisiae
Ng 1777

Saccharomyces cailsbergensis
Saccharomyces carlsbergensis
Ng 3010

95.3

99.8 From Table III it can be seen that there was no difference in Saccharomyces carlsbergensis Ng3010 the yield indicates whether the sugar is sucrose or raffinose, while in the breeding experiment with raffinose-containing molasses the yield in Saccharomyces cerevisiae Kg 1777 is considerably less.

The value of the gas formation and the standing quality of various baker's yeasts was determined by hand the amount of the gas generated in the ι eig for yeast in the fresh state or with the same amount yeast stored at 21 ° C for 7 days (according to the method described in The Journal of the Institut of Brewing, 3d. 65 [1959], p. 39).

The experiments were carried out eight times. The results are summarized in Table IV.

Table IV

yeast

Sacch. carlsb. Ng 3010
Sacch. cerev. Ng 740
Sacch. cerev. Ng 1777
Sacch. cerev. ATCC 13 601
Sacch. cerev. ATCC 13602

ml COj 0 to 45 minutes

54
56
52
45
50

69 69 69 60 66 ml CO ₂ 0 to 90 minutes

123
125
121
105
116

ml of CO ₂

after 7 days cm

Store at 21 ° C

0 to 90 minutes

97 99 97 80 63

Stability calculated on the

Gas generation 0 to 90 minutes

79 79 80 76 54

The quality of the five baker's yeasts, based on bread volume, was determined in baking tests in which the bread volume was measured. The same amount of dough was used for the different yeasts. Baking batch: 2 kg flour, 2% salt, 53% water. The amount of yeast was varied. Kneading time: 8 minutes.

Management scheme:
60 minutes dough rest,
30 minutes; measured intermediate proof,
55 minutes piece cooked.

The dough was processed mechanically; the working temperature was 27 ° C.

Two amounts of yeast were used for each type of yeast. In each case the average volume of three loaves of bread baked with the same Yeast plotted against yeast levels graphically.

For a given standard volume, the ratio between the values of the different which baker's yeast charged. In Table V di <

Results compiled.

Table V

salary Gram yeast Average of dry matter per 50 kg of flour Bread volume L ^% ml Sacch. carlsb. Ng 3010 27.6 700 3600 850 3895 Sacch. cerev. Ng 740 28.2 700 3665 850 3975 Sacch. cerev. Ng 1777 27.9 700 3620 850 3920 Sacch. cerev. ATCC 13601 29.5 800 3435 950 3700 Sacch. cerev. ATCC 13602 27.8 '700 3470 850 3750

By intrapolation or extrapolation were the following quality ratios are calculated for a standard volume of 3700 ml per 800 g bread:

100 parts by weight Ng 740 = 103 parts by weight
of Ng 1777 = 105 parts by weight of Ng 3010

= 115 parts by weight ATCC 13602 = 133 parts by weight ATCC 13601.

The above values show that the Bac quality of the yeast produced according to the invention bride Ng 3010 is the same as the 'of Ng 740 ui Ng 1777. The differences in quality between this hybrid and the DCL hybrids ATCC 136 and ATCC 13601 are such that they not only a test bakery with special devices, also in the usual bakeries in practice fe can be placed.

309 * 1 W

Claims (3)

Patent claims: 1. Process for the production of baker's yeast, characterized in that Saccharomyces carlsbergensis Ng 3010 in the usual Wise breeds 2. The method according to claim 1, characterized in that that the cultivation is carried out in molasses containing RafSnose 3. Use of the baker's yeast produced according to claims 1 and 2 for the production of baked goods.